Lockup damper, lockup mechanism and damper mechanism of torque converter

ABSTRACT

A lockup damper included in a lockup mechanism 8 of a torque converter 1 includes a piston member 9, a driven member 10, coil springs 13 and seat members 40. The coil spring 13 is arranged between the piston member 9 and the driven member 10. The seat member 40 is attached to the driven member 10, has a loose`-fit portion 40c loosely fitted to the end of the coil spring 13, and restricts the radially outward movement of the end of the coil spring 13 by the loose-fit portion 40c fitted into the coil spring 13.

BACKGROUND OF THE INVENTION

A. Field of the Invention

The present invention relates to a damper mechanism, and in particularto a lockup damper and a lockup mechanism in a torque converter formechanically transmitting a torque from an input rotary member to anoutput rotary member.

B. Description of the Background Art

In general, the damper mechanism transmits a torque from an input rotarymember to an output rotary member, and simultaneously operates to absorbor damp a vibration transmitted from the input rotary member toward theoutput rotary member. A lockup mechanism disposed inside the torqueconverter is one example of the above damper mechanism.

The torque converter is internally provided with three kinds of vanewheels, i.e., an impeller, a turbine and a stator, and is operable totransmit a torque through a working fluid filling an internal spacethereof. The impeller is fixed to a front cover coupled to the inputrotary member. The working fluid flowing from the impeller to theturbine through the stator transmits a torque from the impeller to theturbine, and then is transmitted to the output rotary member coupled tothe turbine.

The lockup mechanism is disposed between the turbine and the front coverfor mechanically coupling the front cover and the turbine together andthereby directly transmitting the torque from the input rotary member tothe output rotary member.

Usually, the lockup mechanism has a piston member which can be pressedagainst the front cover, a retaining plate fixed to the piston member,coil springs carried by the retaining plate and a driven memberelastically coupled, in a rotating direction of the mechanism, to thepiston member through the coil springs. The driven member is fixed tothe turbine coupled to the output rotary member. The components of thelockup mechanism also form a lockup damper mechanism for absorbing anddamping an applied vibration.

When the lockup mechanism operates, the piston member slides on or ispressed to the front cover so that the torque is transmitted from thefront cover to the piston member, and then is transmitted to the turbinethrough the coil springs. The lockup mechanism transmits the torque, andalso operates to absorb or damp the torsional or angular vibration owingto the lockup damper. The coil springs are repetitively compressedbetween the retaining plate fixed to the piston member and the drivenmember, and thereby slide on the retaining plate so that the vibrationis damped. A minute torsional vibration is absorbed by repetitiveelastic deformation (expansion and contraction) of the coil springs.

In the conventional lockup damper described above, outer portions, inthe radial direction of the damper, of the coil springs are covered withouter bent portions of the retaining plate, i.e., outer peripheralportions which are bent.

When the lockup mechanism operates and the respective portions rotate,centrifugal forces act on the coil springs and other portions of thetorque convertor so that the coil springs as well as spring seatssupporting the opposite ends of the coil springs are pressed against theouter bent portions of the retaining plate. When the coil springs inthis state expand and contract, the ends of the coil springs and thespring seats attached to the spring ends cause a frictional resistancewith respect to the outer peripheral portions so that the dampercharacteristics change. In particular, the minute torsional vibrationcannot be absorbed sufficiently due to presence of the frictionalresistance.

A large torsional vibration often occurs during clutch engaging anddisengaging operations of the lockup mechanism. In this case, thefrictional resistance, if present, can effectively absorb the vibration.The damper characteristics having the above characteristics areeffective in some kinds of vehicles.

The lockup mechanism provided at its radially outer portion with thecoil or torsion springs can reduce an axial size of the torque convertercompared with the lockup mechanism provided at its radially middleportion with the torsion springs, but cannot ensure a sufficiently largetorsion angle compared with the latter. If the torsion springs areshifted from the middle position to the outer position without changingthe size of the springs, an allowed maximum torsion angle between theinput rotary member and the output rotary member decreases. As a result,the allowed maximum torsion angle of the lockup mechanism decreases,which reduces the property of absorbing the torsional vibrationparticularly in a low rotation speed range of the engine.

In order to overcome the above problems, such a structure may beemployed that two or more torsion springs are arranged in series with anintermediate member(s) therebetween for increasing a total compressiblesize of the elastic member. This structure can provide the largetorsional angle of the lockup mechanism.

However, the torsion spring having a circumferentially increased size islikely to be deformed such that a circumferentially middle portionprotrudes radially outward when compressed. This tends to increase africtional resistance between the torsion spring and a member disposedradially outside the spring. Since the lockup mechanism in the engagedstate rotates together with the torque converter, a centrifugal forceacts on the torsion springs. Due to this, the torsion springs tend tomove radially outward and cause a frictional resistance with membersarranged outside the springs. When the frictional resistance between thetorsion springs and the outer members increases, the torsional vibrationcannot be absorbed sufficiently.

SUMMARY OF THE INVENTION

An object of the invention is to suppress a frictional resistance of anend of a coil spring (elastic member) or a spring seat (seat member)attached to the end of the coil spring with respect to an outer bentportion (a holding portion of the input member) of the retaining plate,and thereby improve a property of absorbing a minute torsionalvibration.

Another object of the invention is to provide a lockup damper or adamper mechanism which can achieve the above object and can alsoeffectively damp a relatively large vibration occurring at the times ofengagement and disengagement of a clutch.

Still another object of the invention is to provide a lockup mechanismof a torque converter having elastic members arranged in series, inwhich a radially outward movement of the elastic member is restricted,and thereby a frictional resistance between the elastic member andanother member is reduced.

According to a first aspect of the invention, a lockup damper of atorque converter is included in a lockup mechanism of the torqueconverter. The lockup mechanism is provided for mechanicallytransmitting a torque from an input rotary member to an output rotarymember. The lockup damper is operable to absorb or damp a vibrationtransmitted from the input rotary member to the output rotary member.The lockup damper of the torque converter comprises an input member, anoutput member, a coil-shaped elastic member and a seat member. The inputmember is supplied with the torque from the input rotary member. Theoutput member outputs the torque to the output rotary member. Theelastic member is arranged between the input member and the outputmember. The seat member is attached to the input or output member, andhas a loose-fit portion to be loosely fitted to an end of the elasticmember. The seat member restricts a radially outward movement of the endof the elastic member fitted to the loose-fit portion.

The lockup damper thus constructed absorbs and damps a vibrationtransmitted from the input rotary member to the output rotary memberduring an operation of the lockup mechanism to transmit the torque fromthe input rotary member to the output rotary member and operations ofthe lockup mechanism to engage and disengage the input and output rotarymembers with and from each other, respectively.

When a torsional vibration is transmitted from the input rotary memberto the input member, this vibration is absorbed and damped by expansionand contraction of the elastic member arranged between the input memberand the output member. During this operation, a centrifugal force isapplied radially outwardly to the elastic member. In the lockup damperof this aspect, the seat member is attached to the input or outputmember, and a radially outward movement of the end of the elastic memberis restricted in the state that the loose-fit portion of the seat memberis fitted to the end of the elastic member. Thereby, the end of theelastic member subjected to the centrifugal force is restrained frommoving radially outwardly so that it is possible to restrain occurrenceof the frictional sliding between the end of the elastic member andanother member disposed radially outside the elastic member. Therefore,the torsional vibration and particularly the minute torsional vibrationapplied to the input member can be sufficiently absorbed.

In conventional lockup dampers and particularly a lockup damper providedwith a coil-shaped elastic member which does not have an arc-shaped formbut has a straight form, a frictional resistance between an end of theelastic member and another member arranged radially outside the elasticmember adversely affects a property of absorbing a minute torsionalvibration in many cases.

Accordingly, the structure of this aspect is particularly effective inthe lockup damper having the elastic member of a straight form.

According to a second aspect, the lockup damper of the torque converterof the first aspect further has such a feature that the input member hasa holding portion disposed radially outside the elastic member and iscircumferentially engaged with the elastic member. The output member isfixed to the output rotary member, and is circumferentially engaged withthe elastic member. The seat member is attached to the output member.

The elastic member is circumferentially engaged with the input andoutput members and thereby elastically couples both the memberstogether. The seat member is attached to the output member, restrictsthe radially outward movement of the elastic member having the endfitted to the loose-fit portion of the seat member, andcircumferentially supports the elastic member.

When the lockup damper is operating, the input and output members rotaterelatively to each other. In a conventional lockup damper which is notprovided with means for restricting radially outward movement of the endof the elastic member, frictional sliding occurs between the elasticmember forced radially outwardly by a centrifugal force and a holdingportion of the input member arranged radially outside the elastic memberwhen a relative rotation occurs between the input and output members. Ifthe elastic member has a straight form, the sliding occurs particularlybetween the end of the elastic member and the holding portion, whichadversely affects the property of absorbing a minute torsionalvibration.

According to the above aspect of the invention, the lockup dampersuppresses a radially outward movement of the end of the elastic memberwhich rotates relatively to the holding portion of the input member sothat contact and sliding between the end and the holding portion of theinput member are prevented or suppressed. This improves the minutetorsional vibration absorbing property.

When a relatively large vibration occurs, e.g., due to engagement of aclutch, the end of the elastic member may be disengaged from theloose-fit portion of the seat member and thereby may come into contactwith the holding portion of the input member, depending on the directionof the relative rotation between the input and output members. In thiscase, however, the elastic member does not transmit a torque andtherefore a vibration between the input and output members, or the endof the elastic member rotates together with the input member. Therefore,when the elastic member is not fitted to the loose-fit portion, anecessity to restrict the radially outward movement of the end of theelastic member is small.

According to a third aspect, the lockup damper of the torque converterof the second aspect further has such a feature that the seat member isattached to a portion of the output member opposed to the forward end,in the rotating direction of the torque converter, of the elasticmember.

In this aspect, the seat member which can restrict the radially outwardmovement of the end of the elastic member is attached only to theportion opposed to the forward end, in the rotating direction of thetorque converter, of the elastic member, and is not attached to the rearportion, in the rotating direction of the torque converter, of theelastic member.

The input member normally rotates in the rotating direction of thetorque converter. The input member pushes, in the rotating direction ofthe torque converter, the rear end, in the torque converter rotatingdirection, of the elastic member, and this pushing force is transmittedto the output member from the end of the forward end, in the torqueconverter rotating direction, of the elastic member, so that the outputmember rotates in the torque converter rotating direction. Forefficiently absorbing the minute torsional vibration by the elasticmember during this operation, it is desired that frictional slidingbetween the elastic member and the holding portion of the input memberis reduced so as to prevent transmission of the vibration from theholding portion of the input member through the end of the elasticmember to the output member. In this aspect, the seat member is attachedto the portion of the output member opposed to the forward end, in thetorque converter rotating direction, of the elastic member forrestricting the radially outward movement of the end of the elasticmember. Thereby, the sliding between the forward end, in the torqueconverter rotating direction, of the elastic member and the holdingportion is prevented or suppressed, and an unnecessary frictionalresistance is eliminated or reduced compared with the prior art.Thereby, the minute torsional vibration can be sufficiently absorbed.The seat member is not attached to the portion of the output memberopposed to the rear end, in the torque converter rotating direction, ofthe elastic member. During the above operation of the lockup damper, theelastic member, of which rear end, in the torque converter rotatingdirection, is opposed to the output member, does not transmit thetorque, or the rear end thereof in the torque converter rotatingdirection rotates together with the input member. Therefore, even if theelastic member is pushed radially outwardly to come into contact withthe holding portion, no influence is substantially applied to the dampercharacteristics (property of absorbing the minute torsional vibration).

A relatively large torsional vibration occurs due to a shock or the likewhen the clutch of the lockup mechanism is being engaged or disengaged.In this case, the input and output members repeat a large relativerotation in both the rotating directions so that the vibration isdamped. When the output member rotates relatively to the input member inthe direction opposite to the torque converter rotating direction, theforward end, in the torque converter rotating direction, of the elasticmember opposed to the output member is restrained from moving radiallyoutwardly so that there is no or only a little frictional resistancebetween the end of the elastic member and the holding portion.Meanwhile, when the output member rotates relatively to the input memberin the same direction as the rotating direction of the torque converter,the rear end, in the torque converter rotating direction, of the elasticmember opposed to the output member can move radially outwardly withouta restriction, and therefore causes a large frictional resistance withrespect to the holding portion. Owing to this frictional resistancebetween the holding portion and the rear end of the elastic member, inthe torque converter rotating direction, of the elastic member, it ispossible to damp efficiently the torsional vibration which occurs duringthe engaging and disengaging operations of the clutch. The end of theelastic member engaging with the input member rotates together with theholding portion of the input member, and therefore does notsubstantially generate the frictional resistance.

According to a fourth aspect, the lockup damper of the torque converterof the first aspect further has such a feature that the loose-fitportion of the seat member has an end of a converging form.

According to this aspect, even when the elastic member is temporarilydisengaged from the loose-fit portion due to the relative rotationbetween the input and output members, the end of the coil-shaped elasticmember will be reliably fitted to the loose-fit portion again when theinput and output members thereafter rotate relatively to each other inthe opposite direction. For this purpose, the loose-fit portion has theend in the converging form.

According to a fifth aspect, the lockup damper of the torque converterof the first aspect further has such a feature that the lockup damperfurther comprises a holding member disposed radially outside the elasticmember for rotation together with one of the input member and the outputmember. The seat member restricts the radially outward movement of oneend of the elastic member.

In this aspect, the seat member restricts only an end of the elasticmember, and does not restrict the radially outward movement of the otherend.

The input member normally rotates in the rotating direction of thetorque converter. The input member pushes the rear end, in the torqueconverter rotating direction, of the elastic member in the rotatingdirection, and this force is transmitted from the forward end, in thetorque converter rotating direction, of the elastic member to the outputmember so that the output member rotates in the rotating direction ofthe torque converter. For efficiently absorbing the minute torsionalvibration by the elastic member, it is desired that the frictionalsliding between the elastic member and the holding member arrangedradially outside the elastic member occurs to a small extent. In thisaspect, one end of the elastic member is restrained from the radiallyoutward movement so that sliding between the holding member and the oneend of the elastic member rotating relatively to the holding member isprevented or suppressed. Therefore, an unnecessary frictional resistancecan be smaller than that in the prior art. Thereby, the minute torsionalvibration can be sufficiently absorbed.

A relatively large torsional vibration occurs due to a shock or the likeduring the engaging and disengaging operations of the clutch of thelockup mechanism. In this case, the input and output members repeat alarge relative rotation in both the rotating directions so that thevibration is damped. When the output member rotates relatively to theinput member in one of the directions, an end of the elastic member isrestrained from moving radially outwardly so that there is no or only alittle frictional resistance between the end of the elastic member andthe holding portion arranged radially outside the elastic member.Meanwhile, when the output member rotates relatively to the input memberin the other direction, the other end of the elastic member can moveradially outward without a restriction, and therefore causes a largefrictional resistance with respect to the holding member. Owing to thisfrictional resistance between the holding member and the other end ofthe elastic member, it is possible to damp efficiently the torsionalvibration which occurs during the engaging and disengaging operations ofthe clutch.

According to a sixth aspect, of the invention, a lockup damper of atorque converter is included in a lockup mechanism of the torqueconverter. The lockup mechanism is provided for mechanicallytransmitting a torque from an input rotary member to an output rotarymember. The lockup damper is operable to absorb or damp a vibrationtransmitted from the input rotary member to the output rotary member.The lockup damper of the torque converter includes an input member, anoutput member, an elastic member and a seat member. The input member issupplied with the torque from the input rotary member. The output memberoutputs the torque to the output rotary member. The elastic member isarranged between the input member and the output member. The seat memberis attached to an end of the elastic member, and has an engagementportion engageable with at least one of the input and output members.The seat member restricts a radially outward movement of the end of theelastic member with its engagement portion engaged with at least one ofthe input and output members.

The lockup damper thus constructed absorbs and damps a vibrationtransmitted from the input rotary member to the output rotary memberduring an operation of the lockup mechanism to transmit the torque fromthe input rotary member to the output rotary member and operations ofthe lockup mechanism to engage and disengage the input and output rotarymembers with and from each other, respectively.

When a torsional vibration is transmitted from the input rotary memberto the input member, this vibration is absorbed and damped bycompression or the like of the elastic member arranged between the inputmember and the output member. During this operation, a centrifugal forceis applied radially outwardly to the elastic member. In this aspect, theseat member is attached to the end of the elastic member, and theradially outward movement of the end of the elastic member is restrictedby the seat member having the engagement portion engaged with at leastone of the input and output members. Thereby, the end of the elasticmember subjected to the centrifugal force is restrained from movingradially outwardly so that it is possible to restrain occurrence of thefrictional sliding between the end of the elastic member and anothermember disposed radially outside the elastic member. Therefore, thetorsional vibration and particularly the minute torsional vibrationapplied to the input member can be further absorbed.

In conventional lockup dampers and particularly a lockup damper providedwith an elastic member which does not have an arc-shaped form but has astraight form, a frictional resistance between an end of the elasticmember and another member arranged radially outside the elastic memberadversely affects properties of the lockup damper and particularlyproperty of absorbing a minute torsional vibration in many cases. Incontrast to this, the structure of the lockup damper can effectivelyoperate.

According to a seventh aspect, the lockup damper of the torque converterof the sixth aspect further has such a feature that the input member hasa holding portion disposed radially outside the elastic member and iscircumferentially engaged with the elastic member. The output member isfixed to the output rotary member, and is circumferentially engaged withthe elastic member. The elastic member has a coil-shaped form. The seatmember has a first engagement portion, a second engagement portion and asupport portion. The first engagement portion is engageable with theinput member. The second engagement portion is engageable with theoutput member. The support portion circumferentially supports theelastic member. The seat member restricts the radially outward movementof the end of the elastic member with at least one of the first andsecond engagement portions engaged with the input or output member.

The elastic member is circumferentially engaged with the input andoutput members and thereby elastically couples both the memberstogether.

When the lockup damper is operating, the input and output members rotaterelatively to each other. In a conventional lockup damper which is notprovided with means for restricting radially outward movement of the endof the elastic member, frictional sliding occurs between the elasticmember forced radially outwardly by a centrifugal force and a holdingportion of the input member arranged radially outside the elastic memberwhen a relative rotation occurs between the input and output members. Ifthe elastic member has a straight form, the sliding occurs particularlybetween the end of the elastic member and the holding portion, whichadversely affects the property of absorbing a minute torsionalvibration.

According to the lockup damper of this aspect, the seat member attachedto the end of the elastic member is engaged with the input or outputmember to restricts the radially outward movement of the end of theelastic member engaging seated on the seat member. When the firstengagement portion is not engaged with the input member due to therelative rotation between the input and output members, the secondengagement portion is engaged with the output member. When the secondengagement portion of the seat member is not engaged with the outputmember, the first engagement portion is engaged with the input member.Thereby, the radially outward movement of the elastic member isrestricted. Therefore, the frictional resistance due to the slidingbetween the end of the elastic member and the input member issuppressed, and therefore the property of absorbing the minute torsionalvibration is improved.

According to an eighth aspect, the lockup damper of the torque converterof the seventh aspect further has such a feature that the first andsecond engagement portions are formed of three claws formed at the seatmember and defining two grooves for loosely fitting the input and outputmembers thereinto, respectively. Each of these claws has an inclinedsurface forming a tip end in a converging form.

In this aspect, when the input member or the output member is disengagedfrom the grooves formed between the three claws due to the relativerotation between the input and output members, the input or outputmember will be reliably fitted into the groove when the input and outputmembers relatively rotates in the opposite direction. For this purpose,the claw has the inclined surface forming the tip end in the convergingform.

According to a ninth aspect, the lockup damper of the torque converterof the sixth aspect further has such a feature that the input member hasa holding portion arranged radially outside the elastic member. The seatmember has an engagement portion engageable with the output member andis attached to the forward end, in the rotating direction of the torqueconverter, of the elastic member. The seat member restricts the radiallyoutward movement of the end of the elastic member when the engagementportion is engaged with the output member.

In this aspect, the seat member capable of restricting the radiallyoutward movement of the end of the elastic member is attached only tothe forward end, in the rotating direction of the torque converter, ofthe elastic member, and is not attached to the rear end, in the rotatingdirection of the torque converter, of the elastic member.

The input member usually rotates in the rotating direction of the torqueconverter. The input member pushes the rear end, in the rotatingdirection of the torque converter, of the elastic member in the rotatingdirection, and the pushing force is transmitted from the forward end, inthe rotating direction of the torque converter, of the elastic member tothe output member, so that the output member rotates in the rotatingdirection of the torque converter. For efficiently absorbing the minutetorsional vibration by the elastic member during this operation, thefrictional sliding between the elastic member and the holding portion ofthe input member is desired to be small. In this aspect, since the seatmember is attached to the forward end, in the torque converter rotatingdirection, of the elastic member, the sliding between the forward end,in the torque converter rotating direction, of the elastic member andthe holding portion is prevented or suppressed, so that an unnecessaryfrictional resistance is eliminated or reduced compared with the priorart. Thereby, the property of absorbing the minute torsional vibrationis improved. The seat member is not attached to the rear end, in therotating direction of the torque converter, of the elastic member.During the above operation of the lockup damper, the rear end, in thetorque converter rotating direction, of the elastic member rotatestogether with the input member. Therefore, even if the end of theelastic member is pushed radially outward to come into contact with theholding portion, this does not substantially affect the dampercharacteristics (minute torsional vibration absorbing property).

During the engaging and disengaging operations of the clutch of thelockup mechanism, a relatively large vibration occurs due to a shock orthe like. In this case, the input and output members repeat the relativerotation to damp the vibration. In this aspect, when the output memberrotates relatively to the input member in the direction opposite to thetorque converter rotating direction, the forward end, in the torqueconverter rotating direction, of the elastic member is restrained fromthe radially outward movement owing to the engagement of the engagementportion of the seat member with the output member, and thereforeproduces no or only a small frictional resistance. Conversely, when theoutput member rotates relatively to the input member in the samedirection as the torque converter rotating direction, a large frictionalresistance occurs between the rear end, in the torque converter rotatingdirection, of the elastic member and the holding portion, because theseat member for restricting the radially outward movement is notattached to the rear end, in the torque converter rotating direction, ofthe elastic member. Owing to the frictional resistance between the rearend, in the torque converter rotating direction, of the elastic memberand the holding portion, it is possible to damp efficiently thevibration which occurs during the engaging and disengaging operations ofthe clutch. The end of the elastic member engaged with the input memberrotates together with the holding portion of the input member, andtherefore does not substantially generate the frictional resistance.

According to a tenth aspect, the lockup damper of the torque converterof the sixth aspect further comprises a holding member arranged radiallyoutside the elastic member and being rotatable together with one of theinput and output members. The seat member restricts the radially outwardmovement of an end of the elastic member.

In this aspect, the seat member restricts only one of the ends of theelastic member and does not restrict the radially outward movement ofthe other end.

The input member usually rotates in the rotating direction of the torqueconverter. The input member pushes the rear end, in the torque converterrotating direction, of the elastic member in the rotating direction, andthe pushing force is transmitted from the forward end, in the torqueconverter rotating direction, of the elastic member to the outputmember, so that the output member rotates in the torque converterrotating direction. For efficiently absorbing the minute torsionalvibration by the elastic member during this operation, the frictionalsliding between the elastic member and the holding member is desired tobe small. The radially outward movement of one end of the elastic memberis restricted, the sliding between the one end of the elastic memberrelatively to the holding member and the elastic member is eliminated orsuppressed, so that an unnecessary frictional resistance is reducedcompared with the prior art. Thereby, the minute torsional vibration issufficiently absorbed.

During the engaging and disengaging operations of the clutch of thelockup mechanism, a relatively large vibration occurs due to a shock orthe like. In this case, the input and output members repeat the largerelative rotation in both the rotating directions to damp the vibration.In this aspect, when the output member rotates relatively to the inputmember in one of the directions, an end of the elastic member isrestrained from the radially outward movement, and therefore produces noor only a small frictional resistance with respect to the holding memberarranged radially outside the elastic member. Conversely, when theoutput rotates relatively to the input member in the other direction, alarge frictional resistance occurs between the other end of the elasticmember and the holding member, because the other end of the elasticmember is not restrained from the radially outward movement. Owing tothe frictional resistance between the other end of the elastic memberand the holding member, it is possible to damp efficiently the vibrationwhich occurs during the engaging and disengaging operations of theclutch.

According to an eleventh aspect of the invention, a damper mechanism isprovided for mechanically transmitting a torque from an input rotarymember to an output rotary member while absorbing and damping avibration transmitted from the input rotary member to the output rotarymember, and comprises an input member, an output member, an elasticmember, a holding member and a seat member. The input member is suppliedwith the torque from the input rotary member. The output member outputsthe torque to the output rotary member. The elastic member elasticallycouples the input member and the output member together in the rotatingdirection. The holding member is arranged radially outside the elasticmember, and rotates together with one of the input and output members.The seat member is arranged between an end of the elastic member and theinput or output member for circumferentially supporting the elasticmember and restricting a radially outward movement of the one end of theelastic member.

When a torsional vibration is transmitted from the input rotary memberto the input member, this vibration is absorbed and damped bycompression or the like of the elastic member arranged between the inputmember and the output member. During this operation of the dampermechanism, a centrifugal force is applied radially outwardly to theelastic member. Therefore, if the radially outward movement of the endof the elastic member is not restricted, a frictional resistance isgenerated by the sliding between the end of the elastic member and theholding member arranged radially outside the elastic member.

The input member usually rotates in the rotating direction of the inputrotary member. The input member pushes the rear end, in the rotatingdirection of the input rotary member, of the elastic member in therotating direction, and the pushing force is transmitted from theforward end, in the rotating direction of the input rotary member, ofthe elastic member to the output member, so that the output memberrotates in the rotating direction of the input rotary member. Forefficiently absorbing the minute torsional vibration by the elasticmember during this operation, the frictional sliding between the elasticmember and the holding member is desired to be small.

During the engaging and disengaging operations of the clutch of thelockup mechanism, a relatively large vibration occurs due to a shock orthe like. In this case, the input and output members repeat the largerelative rotation in both the rotating directions to damp the vibration.In some cases, the vibration can be damped efficiently by utilizing alarge frictional resistance, and therefore it is desired to generatepositively the frictional resistance between the end of the elasticmember and the holding member.

The structure in this aspect restricts the radially outward movement ofonly the one end of the elastic member, and does not restrict theradially outward movement of the other end. Therefore, when the outputmember rotates relatively to the input member with respect to the inputmember, the radially outward movement of the one end of the elasticmember is restricted, and the frictional resistance between the one endand the holding member is suppressed. Thereby, the minute torsionalvibration transmitted to the input member can be absorbed sufficiently.Conversely, when the output member rotates relatively to the inputmember in the other rotating direction, a relatively large frictionalresistance occurs due to the sliding between the other end and of theelastic member and the holding member because the radially outwardmovement of the other end is not restricted. By the frictionalresistance between the other end of the elastic member and the holdingmember, it is possible to damp efficiently the vibration which occursduring the engaging and disengaging operations of the clutch.

According to a twelfth aspect, the damper mechanism of the eleventhaspect further has such a feature that the seat member has an engagementportion engageable with an end of the elastic member and is attached tothe input or output member.

In this aspect, the seat member is attached to the input member or theoutput member, and the engagement portion of the seat member is engagedwith the one end of the elastic member to restrict the radially outwardmovement of the one end of the elastic member.

According to a thirteenth aspect, the damper mechanism of the eleventhaspect further has such a feature that the seat member has an engagementportion to be engaged with at least one of the input and output members,and is attached to one end of the elastic member.

In this aspect, the seat member is attached to the end of the elasticmember, and the engagement portion of the seat member is engaged withthe input or output member for restricting the radially outward movementof the one end of the elastic member.

According to a fourteenth aspect, a lockup mechanism of a torqueconverter is provided for mechanically transmitting a torque from aninput rotary member to an output rotary member in a first rotationdirection while absorbing and damping a vibration transmitted from theinput rotary member to the output rotary member. The lockup mechanismcomprises a damper, an input member and an output member. The damper hasa first elastic member, a second elastic member and an intermediatemember. The second elastic member is arranged forward in a secondrotating direction of the torque converter with respect to the firstelastic member. The intermediate member has an intermediate supportportion arranged between the forward end, in the second rotatingdirection, of the first elastic member and the forward end, in the firstrotating direction, of the second elastic member for allowing torquetransmission between the first and second elastic members. The inputmember includes a circular plate-like piston, an input support portionand a first movement restricting portion. The circular plate isfrictionally engageable and dis-engagable with the input rotary member,and is provided at its outer peripheral portion with the damper. Theinput support portion is arranged at the radially outer portion of thepiston, and supports the forward end, in the first rotating direction,of the first elastic member and the forward end, in the second rotatingdirection, of the second elastic member. The first movement restrictingportion restricts the radially outward movement of the forward end, inthe first rotating direction, of the first elastic member and theforward end, in the second rotating direction, of the second elasticmember. The output member has an output support portion and a secondmovement restricting portion. The output member outputs the torque tothe output rotary member. The output support portion support the forwardend, in the first rotating direction, of the first elastic member andthe forward end, in the second rotating direction, of the second elasticmember. The second movement restricting portion restricts the radiallyoutward movement of the forward end, in the first rotating direction, ofthe first elastic member and the forward end, in the second rotatingdirection, of the second elastic member.

According to the lockup mechanism of the fourteenth aspect, when thepiston of the input member is coupled to the input rotary member, thetorque is transmitted from the input rotary member to the output rotarymember through the lockup mechanism. In the lockup mechanism, the inputsupport portion of the input member moves the damper to push the outputsupport portion of the output member.

When a torsional vibration is transmitted from the input rotary memberto the lockup mechanism, the input and output members rotate relativelyto each other, and the damper, i.e., the first and second elasticmembers are compressed in the rotating direction between the input andoutput support portions. In this aspect, since the first and secondelastic members are arranged in series with the intermediate supportportion of the intermediate member therebetween, so that characteristicsexhibiting a large maximum torsional angle can be ensured. The firstmovement restricting portion provided at the input member and the secondmovement restricting portion provided at the output member restrict theradially outward movement of the circumferentially opposite ends of thedamper (i.e., the forward end, in the first rotating direction, of thefirst elastic member and the forward end, in the second rotatingdirection, of the second elastic member). As a result, the first andsecond elastic members which are compressed in the rotating directionare unlikely to interfere with other members, so that the frictionalresistance is reduced.

According to a fifteenth aspect, the lockup mechanism of the fourteenthaspect further has such a feature that the plurality of dampers arearranged along the rotating direction. The intermediate support portionis provided with a third movement restricting portion for restrictingthe radially outward movement of the forward end, in the second rotatingdirection, of the first elastic member and the forward end, in the firstrotating direction, of the second elastic member. The intermediatemember has a coupling portion for coupling the plurality of intermediatesupport portions together.

According to the lockup mechanism of the fifteenth aspect, since theintermediate support portion is provided with the third movementrestricting portion, the ends of the first and second elastic membersforming the intermediate portion, in the rotating direction, of thedamper are restrained from moving radially outwardly, so that thefrictional resistance of the first and second elastic members withrespect to other members is reduced. In particular, all the portions ofthe first and second elastic members forming the opposite ends and theintermediate portion, in the rotating direction, of the damper arerestrained from moving radially outwardly, so that the frictionalresistance of the first and second elastic members with respect to othermembers is significantly reduced.

According to a sixteenth aspect, the lockup mechanism of the fourteenthaspect further has such a feature that the first movement restrictingportion is arranged radially outside the forward end, in the firstrotating direction, of the first elastic member and the forward end, inthe second rotating direction, of the second elastic member.

According to the lockup mechanism of the sixteenth aspect, the firstmovement restricting portion can be in contact with the outer peripheralportions of the forward end, in the first rotating direction, of thefirst elastic member and the forward end, in the second rotatingdirection, of the second elastic member, and thereby can restrict theradially outward movement of these ends. Therefore, a superior effectcan be achieved by the simple structure.

According to a seventeenth aspect, the lockup mechanism of the sixteenthaspect further has such a feature that the inner peripheral surface ofthe first movement restricting portion can be in contact with theforward end, in the first rotating direction, of the first elasticmember and the forward end, in the second rotating direction, of thesecond elastic member, and the inner peripheral surface of the firstmovement restricting portion is operable to guide radially inwardly theforward end, in the first rotating direction, of the first elasticmember and the forward end, in the second rotating direction, of thesecond elastic member when the forward end, in the first rotatingdirection, of the first elastic member and the forward end, in thesecond rotating direction, of the second elastic member are pressedagainst the inner peripheral surface of the first movement restrictingportion.

According to the lockup mechanism of the seventeenth aspect, when theforward end, in the first rotating direction, of the first elasticmember and the forward end, in the second rotating direction, of thesecond elastic member are pressed against the inner peripheral surfaceof the first movement restricting portion, both the ends are guidedradially inwardly by the inner peripheral surface thereof. Therefore,even if the first movement restricting portion does not restrict theradially outward movement of the ends of the first and second elasticmembers in the free state, the first movement restricting portionreliably guides the ends of the first and second elastic membersradially inwardly when the first and second elastic members arecompressed, so that a sufficient space can be kept between the first andsecond elastic members and members arranged radially outside the same.As a result, an unnecessary frictional resistance is unlikely to occurduring transmission of the torsional vibration.

According to an eighteenth aspect, the lockup mechanism of thefourteenth aspect further has such a feature that the second movementrestricting portion is arranged radially outside the forward end, in thefirst rotating direction, of the first elastic member and the forwardend, in the second rotating direction, of the second elastic member.

According to the lockup mechanism of the eighteenth aspect, the secondmovement restricting portion can be in contact with the outer peripheralportions of the forward end, in the first rotating direction, of thefirst elastic member and the forward end, in the second rotatingdirection, of the second elastic member, and thereby can restrict theradially outward movement of these ends. Therefore, a superior effectcan be achieved by the simple structure.

According to a nineteenth aspect, the lockup mechanism of the eighteenthaspect further has such a feature that the inner peripheral surface ofthe second movement restricting portion can be in contact with theforward end, in the first rotating direction, of the first elasticmember and the forward end, in the second rotating direction, of thesecond elastic member, and is operable to guide radially inwardly theforward end, in the first rotating direction, of the first elasticmember and the forward end, in the second rotating direction, of thesecond elastic member when the forward end, in the first rotatingdirection, of the first elastic member and the forward end, in thesecond rotating direction, of the second elastic member are pressedagainst the inner peripheral surface of the second movement restrictingportion.

According to the lockup mechanism of the nineteenth aspect, when theforward end, in the first rotating direction, of the first elasticmember and the forward end, in the second rotating direction, of thesecond elastic member are pressed against the inner peripheral surfaceof the second movement restricting portion, both the ends are guidedradially inwardly by the inner peripheral surface thereof. Therefore,even if the second movement restricting portion does not restrict theradially outward movement of the ends of the first and second elasticmembers in the free state, the second movement restricting portionreliably guides the ends of the first and second elastic membersradially inwardly when the first and second elastic members arecompressed, so that a sufficient space can be kept between the first andsecond elastic members and members arranged radially outside the same.As a result, an unnecessary frictional resistance is unlikely to occurduring transmission of the torsional vibration.

According to a twelfth aspect, the lockup mechanism of the fourteenthaspect further has such a feature that the output member has acylindrical portion arranged radially outside the first and secondelastic members, and the output support portion and the cylindricalportion are relatively rotatably and axially dis-engagably engagedtogether.

In the lockup mechanism according to the twentieth aspect, thecylindrical portion is arranged radially outside the first and secondelastic members, and prevents a radially outward displacing of theelastic members. Since the output support portion and the cylindricalportion are formed of independent members, the parts increase in numberbut each part can have a simple structure, which allows easy working orprocessing of the whole structure.

According to a twenty-first aspect, the lockup mechanism of thetwentieth aspect further has such a feature that the second movementrestricting portion is formed of portions located near the oppositeends, in the rotating direction of the damper, of the cylindricalportion and protruding radially inwardly beyond the other portion.

In the lockup mechanism according to the twenty-first aspect, the secondmovement restricting portion is formed by partially deforming thecylindrical portion, and therefore can be worked and processed easily.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription, when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side cross section of a lockup clutch in a torque converterin accordance with a first embodiment of the present invention;

FIG. 2 is an end view of a piston member, a retaining plate, coilsprings and coupling members of the lockup clutch depicted in FIG. 1;

FIG. 3 is a fragmentary end view showing a portion of FIG. 2 on enlargedscale, showing details of a seat member of the lockup clutch;

FIG. 4 is a perspective view of the seat member depicted in FIG. 3;

FIG. 5 is a fragmentary view similar to FIG. 3, showing details of aseat member in accordance with a second embodiment of the presentinvention;

FIG. 6 is a perspective view of the seat member depicted in FIG. 5;

FIG. 7 is an end view similar to FIG. 2, showing a piston member, aretaining plate, coil springs and coupling members in accordance with athird embodiment of the present invention;

FIG. 8 is fragmentary a cross section view taken along line VIII--VIIIin FIG. 7;

FIG. 9 is a fragmentary cross section view taken along line IX--IX inFIG. 7;

FIG. 10 is a fragmentary cross section view, on an enlarged scale,showing details of a seat member in accordance with the third embodimentdepicted in FIGS. 7, 8 and 9;

FIG. 11 is a side view of the seat member depicted in FIG. 10, shownremoved from the lockup clutch;

FIG. 12 is an elevation of the seat member depicted in FIG. 11, viewedalong line XII--XII in FIG. 11;

FIG. 13 is a part elevation, part cutaway, part cross section end viewof a lockup mechanism of a torque converter in accordance with afourth-embodiment of the present invention;

FIG. 14 is a fragmentary, cross section taken along line XIV--XIV inFIG. 13;

FIG. 15 is a cross section taken along line XV--XV in FIG. 13;

FIG. 16 is an elevation of a drive plate in accordance with the fourthembodiment of the present invention depicted in FIGS. 13, 14 and 15,showing the drive plate removed from the lockup clutch;

FIG. 17 is an elevation of an intermediate plate in accordance with thefourth embodiment of the present invention depicted in FIGS. 13, 14 and15, showing the intermediate plate removed from the lockup clutch;

FIG. 18 is an elevation of a support ring in accordance with the fourthembodiment of the present invention depicted in FIGS. 13, 14 and 15,showing the support ring removed from the lockup clutch;

FIG. 19 is a side view of the support ring looking in the direction ofthe arrow XIX in FIG. 18; and

FIG. 20 is a fragmentary cross section view of a lockup mechanism inaccordance with the fourth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

A torque converter 1 shown in FIG. 1 includes a front cover 3, a torqueconverter main unit, which is formed of an impeller 4, a turbine 5 and astator (not shown), and a lockup mechanism 8. In FIG. 1, an engine istypically disposed to the left side of FIG. 1 and a transmission on theright side of FIG. 1. Hereinafter, for the purpose of providingdirectional orientation, the left side of FIG. 1 will be referred to asthe engine side, and the right side of FIG. 1 will be referred to as thetransmission side.

The front cover 3 and a shell of the impeller 4 define a working fluidchamber filled with working fluid. The impeller 4, turbine 5 and stator(not shown) have the same structures as those in the prior art, andtherefore will not be described below in detail. A shell of the turbine5 is fixed at its inner peripheral portion to a turbine hub 6 by rivets24. The turbine hub 6 is spline-fitted to a shaft (not shown) extendingfrom a transmission.

The lockup mechanism 8 is provided for selectively mechanicallytransmitting torque from the front cover 3 to the turbine 5 and turbinehub 6, and for absorbing and damping a vibration transmitted thereto.The lockup mechanism 8 is basically formed of an input piston member 9,an output driven member 10, four elastic members, i.e., four coilsprings 13, a retaining plate 14, and a coupling member 30.

The piston member 9 is operable to move toward and away (back and forth)from the front cover 3 in accordance with changes of the hydraulicpressure in the torque converter main unit in a manner well known in theart. The piston member 9 is substantially formed of a circular plate,and has cylindrical portions 9a and 9b at its outer and innerperipheries, respectively. The outer and inner cylindrical portions 9aand 9b extend toward the transmission (rightward in FIG. 1). The innercylindrical portion 9b is supported relatively rotatably and axiallymovably on the outer peripheral surface of the turbine hub 6. When theclutch of the lockup mechanism is disengaged, the inner cylindricalportion 9b is in contact with the turbine hub 6, and can axially moveonly toward the front cover 3. A side surface of the outer peripheralportion of the piston member 9 is covered with a circular frictionfacing 20 which is fixed thereto and is opposed to the friction surfaceof the front cover 3.

The retaining plate 14 is provided for supporting the four coil springs13 on the piston member 9. The retaining plate 14 is arranged radiallyinside the outer cylindrical portion 9a of the piston member 9. Theretaining plate 14 has an outer bent portion 16 having an arc-shapedsection. The outer peripheral surface of the outer bent portion 16 is incontact with the inner peripheral surface of the outer cylindricalportion 9a. As shown in FIGS. 1 and 2, the outer peripheral portion 16is provided at circumferentially two equally space positions,diametrically opposed to each other, with circumferential supportportions 17a and 17b which are bent and projected toward the innerperiphery and the transmission. A fixing portion 18 extends radiallyinward from each set of the circumferential support portions 17a and17b. Each fixing portion 18 extends circumferentially over apredetermined angle, and is fixed to the piston member 9 by three rivets21.

The driven plate 10 is substantially formed of an annular plate, and iswelded to the outer peripheral portion of the shell of the turbine 5.Two support portions 10a protrude toward the engine side from the drivenmember 10. Each support portion 10a extends between the circumferentialsupport portions 17a and 17b of the retaining plate 14. A seat member 40is attached to the support portion 10a, as shown in FIG. 3. The seatmember 40 is slidable between the circumferential support portions 17aand 17b.

The seat member 40 has radially outer and inner peripheral surfaces 40ewhich are complementary in shape to circumferential support portions 17aand 17b, respectively, as shown in FIG. 4 and is circumferentiallymovably fitted between the circumferential support portions 17a and 17bas shown in FIG. 3. The seat member 40 is formed with a fitting portion40b having an opening 40a, into which the support portion 10a of thedriven member 10 is fitted, loose-fit portions 40c which are formed atthe circumferentially opposite ends of the fitting portion 40b and areloosely fitted into the circumferential ends of the coil springs 13,respectively, and supporting surfaces 40d which are in contact with thesurfaces of the circumferential ends of the coil springs 13,respectively. Each loose-fit portion 40c has a tapered or convergingform for easy fitting into the coil spring 13. When the loose-fitportion 40c is fitted into the end of the coil spring 13, it restrictsradially outward movement of the end of the coil spring 13. A wholeconfiguration of the seat member 40 is curved along thecircumferentially extending various members, as is shown in FIG. 3.

Each coil spring 13 is operable to transmit torque in the lockupmechanism 8, and is also operable to absorb or damp minute torsionalvibration caused by variation in rotation of the engine and vibrationdue to a shock caused by the engagement operation of the clutch. Thecoil spring 13 elastically couples, in the rotating direction of thetorque converter, the piston member 9 and the driven member 10 togetherthrough the retaining plate 14. As shown in FIG. 2, first and secondcoil springs 13A and 13B are arranged in one of the arc-shaped spacesdefined between two sets of the diametrically opposed circumferentialsupport portions 17a and 17b and the supporting surfaces 40d. Third andfourth coil springs 13C and 13D are arranged in the other of thearc-shaped spaces defined between the diametrically opposedcircumferential support portions 17a and 17b and the supporting surfaces40d. The third and fourth coil springs 13C and 13D have the samestructures as the first and second coil springs 13A and 13B, andtherefore will not be described below.

The first and second coil springs 13A and 13B are arranged in series asshown in FIG. 2, and a spring intermediate seat portion 32 of thecoupling member 30 is interposed between them. The combination of thefirst and second coil springs 13A and 13B exhibits characteristics suchas a large maximum torsion angle (displacement angle) and low rigidity.

The coupling member 30 is provided for radially coupling the coilsprings 13 together and thereby restricting a radially outward movementof the coil springs 13. The coupling member 30 is formed of an annularplate 31 and spring intermediate seat portions 32 provided on theannular plate 31.

The annular plate 31 is relatively rotatably arranged radially insidethe coil springs 13 and axially between the retaining plate 14 and theturbine 5. The annular plate 31 is provided at diametrically opposed twoportions thereof with projections 31a (see FIG. 1) protruding radiallyoutward. One of the projections 31a extends between the first and secondcoil springs 13A and 13B, and the other extends between the third andfourth coil springs 13C and 13D.

The spring intermediate seat portion 32 is fixed to the projection 31afor coupling in series the first and second coil springs 13A and 13Btogether and restricting the radially outward movement of the ends ofthese coil springs 13A and 13B near the spring intermediate seat portion32. In this manner, the ends of the first and second coil springs 13Aand 13B near the spring intermediate seat portion 32 are radiallycoupled together by the coupling member 30, and the ends of the thirdand fourth coil springs 13C and 13D near the spring intermediate seatportion 32 are also radially coupled together the coupling member 30.

Thus, the coupled portions of the coil springs 13 are restrained fromradially outward movement.

Operation of the first embodiment is described below.

When the lockup mechanism 8 is in a disengaged state and the workingfluid between the front cover 3 and the piston member 9 is drained, thepiston member 9 moves toward the front cover 3 so that the frictionfacing 20 comes into close contact with the friction surface of thefront cover 3, thus moving into an engagement state. Thereby, the torqueof the front cover 3 is transmitted to the piston member 9, and isfurther transmitted to the turbine 5 via the retaining plate 14, coilsprings 13 and drive member 10. The torque thus transmitted is outputfrom the turbine hub 6 to the shaft (not shown) extending from thetransmission. The direction of the input torque, i.e., the rotatingdirection of the torque converter 1 is indicated by R1 in FIG. 2.

When minute torsional vibrations are transmitted to the front cover 3with the lockup mechanism in the engagement state, a relative rotationcyclically occurs between the piston member 9 and the driven member 10so that the coil springs 13 circumferentially expand and contract. Inthis operation, the minute torsional vibrations are effectively absorbedowing to the characteristics of the coil springs 13 exhibiting the lowrigidity and the large maximum torsional angle. The compressed coilspring 13 tends to protrude radially outward, and also tends to moveradially outward due to a centrifugal force. However, the coil springs13 coupled together (i.e., the first and second coil springs 13A and 13Bas well as the third and fourth coil springs 13C and 13D) are carried attheir coupled portions by the spring intermediate seat portions 32 andare also supported at their ends by the seat members 40 so that aradially outward movement of them is suppressed. Consequently,frictional sliding is suppressed between the coil springs 13 and theouter bent portion 16. Thus, the frictional resistance occurring betweenthe coil springs 13 and the outer bent portion 16 is small, and the coilsprings 13 can effectively absorb the minute torsional vibration. Whenthe coil springs 13 are in the compressed state, ends of the coilsprings 13 coupled together by the spring intermediate seat portion 32are supported by the loose-fit portion 40c and the support surface 40don the driven member 10. The other end of the springs 13 are carried bythe circumferential support portions 17a and 17b on the piston member 9,and are in contact with the outer bent portion 16. The circumferentialsupport portions 17a and 17b supporting the other end are integral withthe outer bent portion 16 so that sliding hardly occurs between theother ends of the coil springs 13 and the outer bent portion 16.

It should be appreciated that as the coil springs 13 are compressed, theseat members 40 slide circumferentially with respect to the 17 and maymove circumferentially away from the circumferential support portions17a and 17b. However, the shape of the outer and inner peripheralsurfaces 40e assists in guiding the seat members 40 back in between thecircumferential support portions 17a and 17b.

Second Embodiment

A second embodiment uses a seat member 42 shown in FIG. 6 instead of theseat member 40 employed in the first embodiment. Structures of thetorque converter other than features relating to the seat member 42, arethe same as those described above with respect to the first embodiment.

The seat member 42 has outer and inner peripheral surfaces which arecomplementary in shape to the circumferential support portions 17a and17b as shown in FIG. 6, and is circumferentially movably arrangedbetween the circumferential support portions 17a and 17b. The seatmember 42 is formed with a fitting portion 42b having an opening 42afitted to the support portion 10a of the driven member 10, a loose-fitportion 42c which is formed at one of circumferential ends of thefitting portion 42b and can be loosely fitted into the end of the coilspring 13, and a support surface 42d which can be in contact with theend surface (i.e., the surface at the circumferential end) of the coilspring 13. The loose-fit portion 42c is located at the rear of thefitting portion 42b in the rotating direction of the torque converter 1indicated by R1 in FIG. 2. The end of the loose-fit portion 42c has atapered or converging form for easy fitting into the coil spring 13. Theloose-fit portion 42c is fitted into the forward end, in the rotatingdirection of the torque converter 1, of the coil springs 13 coupledtogether by the spring intermediate seat portion 32 so that the seatmember 42 restricts the radially outward movement of the coupled coilsprings 13. The seat member 42 has a curved form as a wholecomplementary to the forms of the circumferentially extending members(see FIG. 5).

Operation of the second embodiment is described below.

The torque is transmitted from the front cover 3 to the shaft (notshown) extending from the transmission in the same manner as the firstembodiment.

When the lockup clutch is in the engagement state, the torque converter1 rotates in the direction indicated by R1 in FIG. 2 so that the coilsprings 13 coupled by the spring intermediate seat portion 32 arecompressed between the support surface 42d of the driven plate 10, whichsupports the forward end, in the rotating direction of the torqueconverter 1, of the springs 13, and the circumferential support portions17a and 17b of the piston member 9, which support the rear end of thesprings 13. When minute torsional vibrations enter the front cover 3while the coil springs 13 is compressed in the above manner, the pistonmember 9 and the driven member 10 cyclically rotate relatively to eachother, and the coil springs 13 circumferentially expand and contract. Inthis operation, the compressed coil springs 13 tend to protrude radiallyoutward, and are also forced radially outward by the centrifugal force.However, the coupled coil springs 13 have the coupled portions supportedby the spring intermediate seat portion 32 as well as one end supportedby the loose-fit portion 42c on the driven member so that the radiallyoutward movement of them is suppressed. As a result, frictional slidingis unlikely to occur between the coil spring 13 and the outer bentportion 16. Thus, a frictional resistance occurring between the coilsprings 13 and the outer bent portion 16 is small so that the coilsprings 13 can effectively absorb the minute torsional vibration. Theother end of the coil springs 13 which are coupled together by thespring intermediate seat portion 32 is supported by the circumferentialsupport portions 17a and 17b on the piston member 9, and is notsupported by a portion or member restricting the radially outwardmovement so that the other end comes into contact with the outer bentportion 16. However, the circumferential support portions 17a and 17bwhich support the other end are integral with the outer bent portion 16so that a sliding hardly occurs between the other end of the coilsprings 13 and the outer bent portion 16.

When the lockup clutch is being engaged or disengaged, a relativelylarge torsional vibration occurs due to a shock or the like. In thisoperation, the piston member 9 and the driven member 10 repeat largerelative rotations in both the directions so that the vibration isdamped. When the driven member 10 rotates relatively to the pistonmember 9 in the direction R2 opposite to the rotating direction of thetorque converter 1, the loose-fit portion 42c restricts the radiallyoutward movement of the forward end, in the rotating direction (R1) ofthe torque converter 1, of the coupled coil springs 13 so that thefrictional sliding is suppressed between the forward end and the outerbent portion 16. Conversely, when the driven member 10 is rotatingrelatively to the piston member 9 in the same direction (R1 in FIG. 2)as the rotating direction of the torque converter 1, the rear end, inthe rotating direction R1 of the torque converter 1, of the coupled coilsprings 13 frictionally slides on the outer bent portion 16 because theradially outer movement of this rear end is not restricted. Owing to theresistance, which is produced by the frictional sliding between the rearend, in the rotating direction R1 of the torque converter 1, of thecoupled coil springs 13 and the outer bent portion 16, it is possible todamp effectively the torsional vibration which occurs during theengaging and disengaging operations of the lockup mechanism.

Third Embodiment

A lockup mechanism 50 of a torque converter of a third embodiment of theinvention shown in FIGS. 7 to 12 is provided for mechanicallytransmitting a torque from the front cover 3 to the turbine 5 whileabsorbing and damping a transmitted vibration. The lockup mechanism 50is basically formed of an input piston member 51, an output drivenmember 52, four elastic members, i.e., coil springs 53 each including aset of large and small coil springs 53a and 53b, a retaining member,i.e., a retaining plate 54, a coupling member 55 and seat members 56.FIG. 7 is a plan showing the lockup mechanism 50 with the driven member52 not shown for greater clarity, and FIGS. 8 and 9 show fragmentarycross sections of the lockup mechanism 50.

The piston member 51 is operable to move toward or away from the frontcover 3 in accordance with selective changes in the hydraulic pressurein the torque converter main unit in a manner know in the art. Thepiston member 51 is substantially formed of a circular plate, and hascylindrical portions 51a and 51b at its outer and inner peripheries. Theouter and inner cylindrical portions 51a and 51b extend toward thetransmission (rightward in FIGS. 8 and 9). The inner cylindrical portion51b is carried relatively rotatably and axially movably on the outerperipheral surface of the turbine hub (not shown). A side surface of theouter peripheral portion of the piston member 51 is covered with thecircular friction facing 20 which is fixed thereto and is opposed to acorresponding friction surface of the front cover 3.

The retaining plate 54 is provided for holding the four sets of coilsprings 53 on the piston member 51. The retaining plate 54 is arrangedradially inside the outer cylindrical portion 51a of the piston member51. The retaining plate 54 has an outer bent portion 54a having anarc-shaped section. The outer peripheral surface of the outer bentportion 54a is in contact with the inner peripheral surface of the outercylindrical portion 51a. The outer peripheral portion 54a is provided atcircumferentially equally spaced four positions with circumferentialsupport portions 54b and 54c which are bent and projected toward theinner periphery and the transmission side. A fixing portion 54d extendsradially inward from each set of the circumferential support portions54a and 54b. Each fixing portion 54d is fixed to the piston member 51 byrivets 59.

The driven plate 52 is substantially formed of an annular plate, and iswelded to the outer peripheral portion of the shell of the turbine 5.Four support portions 52a protrude toward the engine from the drivenmember 52 as shown in FIGS. 8 and 10. Each support portion 52a isarranged between the circumferential support portions 54b and 54c of theretaining plate 54.

The seat member 56 has three claws, i.e., radially outer, middle andinner claws 56a, 56b and 56c as shown in FIGS. 11 and 12, and also has afitting portion 56d, which extends into the large coil spring 53a, and asupporting surface 56e which is in contact with the circumferential endsurface of the large coil spring 53a and supports the large coil spring53a. As shown in FIG. 10, the seat member 56 is engageable with thesupport portion 52a of the driven member 52 and the circumferentialsupport portions 54b and 54c of the retaining plate 54, and is fitted tothe large coil spring 53a. More specifically, the support portion 52a isfitted into a groove between the outer and middle claws 56a and 56b, andthe circumferential support portion 54c is fitted into a groove betweenthe middle and inner claws 56b and 56c.

The radially outward movement of the seat member 56 and the end of thelarge coil spring 53a fitted to the seat member 56 is restricted by thesupport portion 52a when the support portion 52a is fitted into thegroove between the outer and middle claws 56a and 56b, and is alsorestricted by the circumferential support portions 54b and 54c when thecircumferential support portion 54c is fitted into the groove betweenthe middle and inner claws 56b and 56c. The fitting portion 56d andsupporting surface 56e are inclined at an angle as shown in FIG. 10 and11 for better engagement with the coil spring 53a. The tip ends of thethree claws 56a, 56b and 56c, which contact the support portion 52a andthe circumferential support portions 54b and 54c, have inclined surfacesfor easy fitting of the support portion 52a and the circumferentialsupport portions 54b and 54c into the grooves formed between the claws56a, 56b and 56c. The seat member 56 has a configuration allowing easymanufacturing as shown in FIG. 11, and is not a resin molded product buta metal product. It should be understood, that the seat member 56 movesin and out of engagement with the support portion 52a in response tocompression and expansion of the coil springs.

The coil springs 53 are operable to transmit a torque in the lockupmechanism 8, and is also operable to absorb or damp a minute torsionalvibration caused by variation in rotation of the engine and a vibrationdue to a shock caused by the engaging operation of the clutch. In thisembodiment, since the coil spring 53 is formed of the two kinds of,i.e., large and small coil springs 53a and 53b, the dampercharacteristics obtained thereby can have two stages. The coil spring 53elastically couples the piston member 51 and the driven member 52together in the rotating direction through the retaining plate 54. Thelarge and small coil springs 53a and 53b are arranged in series with anintermediate seat portion 55a of the coupling member 55 therebetween.The coupling member 55 is described below. The seat member 56 isattached to the forward end, in the torque converter rotating directionindicated by R1 in FIG. 7, of the large coil spring 53a.

The coupling member 55 is provided for radially coupling the coupledportions of the four sets of coil springs 53 and thereby restricting theradially outward movement of the coupled portions. The coupling member55 is formed of an annular plate 55b and intermediate seat portions 55awhich protrude radially outward from circumferentially spaced fourpositions of the annular plate 55b. The annular plate 55b is locatedradially inside the coil springs 53, and is arranged axially between theretaining plate 54 and the turbine 5 for relative rotation with respectto them. The annular plate 55b is rotatably pressed by arc-shapedpressing plates 57 for restricting the axial movement thereof as shownin FIGS. 7 and 8. The pushing plates 57 are four in number, and arefixed at their inner peripheral portions to the piston member 51 byrivets 60 and the aforementioned rivets 59. The intermediate seatportion 55a couples the large and small coil springs 53a and 53b inseries, and restricts the radially outward movement of the coupledportions of these coil springs 53a and 53b.

Operation of the embodiment shown in FIGS. 7-12 is described below.

During the engaged state of the lockup clutch, the torque converterrotates in the direction R1 in FIG. 7 so that the coil spring 53 iscompressed between the support surface 56e of the seat member 56, whichis fitted to the support portion 52a of the driven member 52 andsupports the forward end, in the rotating direction of the torqueconverter, of the large coil spring 53a, and the circumferential supportportions 54b and 54c of the retaining plate 54, which are fixed to thepiston member 51 and support the rear end of the small coil spring 53b.When a minute torsional vibration is supplied to the front cover 3 inthis state, relative rotation cyclically occurs between the pistonmember 51 and the driven member 52 so that the coil springs 13 arecircumferentially compressed and expanded. In this operation, thecompressed coil springs 13 tend to protrude radially outward, and arealso forced radially outward by the centrifugal force. However, the coilspring 53 has the coupled portion, which is supported by theintermediate seat portion 55a of the coupling member 55. Also, the endof the large coil spring 53a at the forward position in the rotatingdirection of the torque converter is supported by the support portion52a of the driven member 52 through the middle claw 56b of the seatmember 56. Therefore, the radially outward movement of the spring 53 issuppressed. As a result, frictional sliding is unlikely to occur betweenthe coil spring 53 and the outer bent portion 54a. Thus, a frictionalresistance occurring between the coil spring 53 and the outer bentportion 54a is small so that the coil spring 53 can effectively absorbthe minute torsional vibration.

When the lockup clutch is being engaged or disengaged, a relativelylarge torsional vibration occurs due to a shock. In this operation, thepiston member 51 and the driven member 52 repeat large relativerotations in the rotating and reverse directions, whereby the vibrationis damped. When the driven member 52 rotates relative to the pistonmember 51 in the direction (R2 in FIG. 7) opposite to the rotatingdirection of the torque converter, the radially outward movement of thecoil spring 53 is suppressed, because the forward end, in the torqueconverter rotating direction (R1), of the large coil spring 53a of thecoil spring 53 is supported by the support portion 52a of the drivenmember 52 through the middle claw 56b of the seat member 56. Thus, thefractional sliding is suppressed with respect to the outer bent portion54a. Conversely, when the driven member 52 is rotating relatively to thepiston member 51 in the same direction (R1 in FIG. 2) as the rotatingdirection of the torque converter, the rear end, in the rotatingdirection R1 of the torque converter 1, of the small coil spring 53b ofthe coil spring 53 frictionally slides on the outer bent portion 54abecause the radially outer movement of this end is not restricted. Owingto the resistance, which is produced by the frictional sliding betweenthe rear end, in the rotating direction R1 of the torque converter, ofthe coil spring 53 and the outer bent portion 54a, it is possible todamp effectively the torsional vibration which occurs during theengaging and disengaging operations.

In the third embodiment, the seat member 56 is attached only to theforward end, in the rotating direction (R1 in FIG. 7) of the torqueconverter, of the large coil spring 53a. However, if it is intended tosuppress the frictional resistance during the relative rotation in boththe relative rotation directions between the piston member 51 and thedriven member 52 for changing the damper characteristics, another set ofseat members 56 may be attached to the rear end, in the rotatingdirection (R1 in FIG. 7) of the torque converter, of the small coilspring 53b.

Fourth Embodiment

FIGS. 13 to 15 show a lockup mechanism 101 of a torque converter of afourth embodiment of the invention. An engine (not shown) is arranged atthe left side of FIG. 14, and a transmission (not shown) is arranged atthe right side of FIG. 14. In FIG. 13, a first rotating direction R1 isa positive rotating direction of the engine, and a second rotatingdirection R2 is a negative or reverse rotating direction thereof.

FIG. 14 shows a front cover 150 (input rotary member) and a turbine 152(output rotary member) of the torque converter. The front cover 150 is acircular member coupled to the crank shaft of the engine, and definestogether with an impeller (not shown) a working fluid chamber of thetorque converter. A flat annular friction surface 151 is formed at theinner surface of the outer peripheral portion of the front cover 150.The turbine 152 is a vane wheel axially opposed to the impeller (notshown), and is basically formed of a turbine shell 153 and a pluralityof turbine blades 154 fixed to the turbine shell 153. The innerperipheral portion of the turbine shell 153 is coupled to a main driveshaft (not shown) of the transmission through the turbine hub.

The lockup mechanism 101 is provided for mechanically transmitting thetorque from the front cover 150 to the turbine 152 while absorbing anddamping the torsional vibration transmitted thereto. The lockupmechanism 101 has a clutch function and a damper function. The lockupmechanism 101 is arranged in a space between the front cover 150 and theturbine 152 as shown in FIG. 14.

The lockup mechanism 101 is basically formed of an input memberincluding a piston 102, an output member including a driven plate 105,and a damper operating between the input and output members.

The input member is formed of the piston 102 and drive plates 103. Thepiston 102 is a clutch member which can be moved toward or away from thefront cover 150 by controlling hydraulic pressure in the torqueconverter main unit. The piston 102 is a circular member, and has outerand inner projections 111 and 112 at its radially outer and innerportions, respectively. The inner and outer projections 111 and 112 havecylindrical forms and protrude toward the transmission. The innerprojection 111 is relatively rotatably and axially movably supported onthe outer peripheral surface of the turbine hub (not shown). A sidesurface of the outer peripheral portion of the piston 102 opposed to theengine is covered with a circular friction facing 102a fixed thereto andopposed to the friction surface 151 of the front cover 150.

The drive plates 103 are fixed to the piston 102, and are provided forsupporting, in the rotating direction, dampers formed of first andsecond coil springs 107 and 108. The drive plates 103 are arrangedbeside the outer peripheral portion of the piston 102 and radiallyinside the outer cylindrical portion 112, and are located atcircumferentially equally spaced four positions. As shown in FIG. 16,each drive plate 103 is formed of a fixing portion 113 extending in therotating direction, a radially inner engagement portion 114 extendingfrom the outer periphery of the fixing portion 113 toward thetransmission, a concavity 115 located radially outside the innerengagement portion 114 and opened toward the transmission, and aradially outer engagement portion 116 located radially outside theconcavity 115. The inner engagement portion 114, concavity 115 and outerengagement portion 116 form input support portions which can be incontact with the radially inner, middle and outer portions of the firstand second coil springs 107 and 108, respectively. The fixing portion113 is provided with apertures 113 for rivets 110. The drive plate 103is rigidly fixed to the piston 102 by rivets 110 and functions as amember at the input side. Since the input support portions support aplurality of portions at radially different positions of the ends of thefirst and second coil springs 107 and 108, the first and second coilsprings are supported stably. The outer peripheral surface of the outerengagement portion 116 is in contact with the inner peripheral surfaceof the outer projection 112 of the piston 102. This facilitatespositioning of the drive plate 103, and suppresses the deformation ofthe drive plate 103 in the radially outward direction.

The drive plate 103 is provided at circumferentially opposite sides ofthe outer engagement portion 116 with first movement restrictingportions 117 which are projections extending in the rotating direction.The first movement restricting portions 117 support the opposite ends ofthe first and second coil springs 107 and 108, which are describedbelow, and thereby restrict their radially outward movement. The firstmovement restricting portion 117 has a converging form, of which radialwidth decreases as the position moves in the first or second rotatingdirection toward its tip end, and has an inner peripheral surface whichforms a guide surface 118 and inclines with respect to the rotatingdirection to form the above diverging form. In other words, the portionof the guide surface 118 at the tip end is located radially outside theportion thereof at the base end. Therefore, the portions of the firstand second coil springs 107 and 108 which are in contact with the guidesurfaces 118 are located at radially inner positions than the otherportions.

The dampers are provided for the torque transmission and for absorbingand damping the minute torsional vibration or the like due to variationin rotation of the engine. The dampers are arranged at four positions,which are equally spaced from each other in the rotating direction. Eachdamper is formed of the first coil spring 107 (first elastic member),the second coil spring 108 (second elastic member) and an intermediateplate or member 104. The first coil spring 107 is longer in the rotatingdirection than the second coil spring 108, and has a lower rigidity thanthe second coil spring 108. This provides the damper characteristicshaving two stages. In each damper, the first coil spring 107 is locatedforward, in the first rotating direction R1, with respect to the secondcoil spring 108. A first spring seat 130 is arranged at the forward end,in view of the first rotating direction R1, of the first coil spring107. The first spring seat 130 has a circular disk-like support portionand an engagement portion extending from the support portion into thecoil spring. The rear surface of the first spring seat 130 is supportedby the input support portion formed of the inner engagement portion 114,concavity 115 and outer engagement portion 116 of the drive plate 103. Asecond spring seat 131 is arranged at the forward end, in the secondrotating direction R2, of the second coil spring 108. The second springseat 131 has the same structure as the first spring seat 130, and issupported by the drive plate 103.

The intermediate plate 104 is operable between the first and second coilsprings 107 and 108, and has an intermediate support portion 121, whichis arrange between the forward end, in view of the second rotatingdirection R2, of the first coil spring 107 and the forward end, in thefirst rotating direction R1, of the second coil spring 108 for allowingtransmission of the torque between the first and second coil springs 107and 108. The middle support portion 121 has a triangular form convergingradially inwardly, and inclined support surfaces 121a are formed at itsopposite sides in the circumferential direction (R1 and R2). Since thesupporting surfaces 121a are inclined, partial or local contact of thesupport surfaces 121a with the first and second coil springs 107 and 108are suppressed. Therefore, the first and second coil springs 107 and 108as well as the intermediate plate 104 can have long lifetimes. Theintermediate support portion 121 is provided at its opposite sides inthe circumferential direction (R1 and R2) with third movementrestricting portions 122 which protrude in the circumferentialdirection. Each third movement restricting portion 122 extendsperpendicularly from the supporting surface 121a. The third movementrestricting portions 122 are fitted into the forward end in the secondrotating direction R2 of the first coil spring 107 and the forward endin the first rotating direction R1 of the second coil spring 108,respectively. The third movement restricting portions 122 are in contactwith the inner peripheries of the first and second coil springs 107 and108. The plurality of intermediate support portions 121 are coupledtogether by the ring 120 functioning as a coupling portion. In thismanner, the radially outward movement of each intermediate supportportion 121 is restricted. As a result, the radially outward movement ofthe circumferentially intermediate portion of each damper (i.e., theforward end in the second rotating direction R2 of the first coil spring107 and the forward end in the first rotating direction R1 of the secondcoil spring 108) is restricted. Since the intermediate plate 104 is notdirectly supported by another member, a frictional resistance isunlikely to occur.

The output member is formed of the driven plate 105 and the support ring106. The driven plate 105 is a member fixed to the turbine shell 153 ofthe turbine 152, and has an annular portion 105a welded to the turbineshell 153 and a plurality of engagement portions 105b which extend fromthe annular portion 105a toward the transmission and are insertedbetween the ends, in the rotating directions, of the dampers. The engageportion 105b extends through the concavity 115 of the drive plate 103,and has the opposite ends in the rotating directions, which are incontact with the first and second spring seats 130 and 131,respectively. Thus, the engagement portions 105b function as an outputsupport portion.

The support ring 106 is an annular metal plate produced by press workingas shown in FIGS. 18 and 19, and is basically formed of a cylindricalportion 125 and a circular plate portion 126 extending radially inwardfrom the end of the cylindrical portion 125 near the transmission. Thecircular plate portion 126 is provided at circumferentially equallyspaced four positions of its inner periphery with recessed engagementportions 127. The engagement portions 105b of the driven plates 105 areinserted into and engaged with the recessed engagement portions 127,respectively. Thereby, the support ring rotates together with he drivenplate 105. The engagement portion 105b and the recessed engagementportion 127 engaged together are axially disengagable from each other.At each position provided with the recessed engagement portion 127, thecircular plate portion 126 is bent toward the transmission to form aspring engagement portion 128. The spring engagement portion 128supports the first and second spring seats 130 and 131. Thus, the springengagement portion 128 forms the support portion at the output sidetogether with the engagement portion 105b of the driven plate 105. Sincethe spring engagement portion 128 and the engagement portion 105bsupport the first and second coil springs 107 and 108 at radiallydifferent positions, an effect similar to that by the support portion atthe input side can be achieved.

The cylindrical portion 125 is located radially inside the outerprojection 112, and covers the outer periphery of each damper, i.e.,first and second coil springs 107 and 108. The cylindrical portion 125is located near the outer projection 112 of the piton 102, but a spaceis kept between them. The cylindrical portion 125 covers the outerperipheries of the first and second coil springs 107 and 108 to preventthe radially outward disengagement thereof. As shown in FIGS. 13 and 20,a large radial space is kept between the cylindrical portion 125 and theouter peripheries of the first and second coil springs 107 and 108 inthe free state. A radial space is also kept between the cylindricalportion 125 and the intermediate support portion 121 of the intermediateplate 104. The cylindrical portion 125 is provided at its four positioncorresponding to the drive plates 103 with second movement restrictingportions 129 which extend linearly through positions radially inside theother arc-shaped portions. The second movement restricting portion 129extends from the vicinity of the drive plate 103 in the first and secondrotating directions, and reaches the positions radially outside the endsof the dampers to cover several turns of the first coil spring 107 atthe forward end thereof in the first rotating direction R1 and severalturns of the second coil spring 108 at the forward end thereof in thesecond rotating direction R2. As a result, the ends of the first andsecond coil springs 107 and 108 are restrained from moving radiallyoutward beyond guide surfaces 129 which are the inner peripheralsurfaces of the second movement restricting portions 129. The guidesurface 129a of the second movement restricting portion 129 is inclinedradially inward with respect to the inner peripheral surfaces of theother arc-shaped portions. More specifically, at portions radiallyoutside the first and second spring seats 130 and 131, the outerportions of the guide surface 129 in the rotating directions are locatedradially inside the inner portion thereof in the rotating directions. Atthe ends of the first and second coil springs 107 and 108, therefore,the portions in contact with the guide surfaces 129a are locatedradially inside the other portions.

The portion forming the second movement restricting portion 129 isprovided with a slit 140, which extends through the cylindrical portion125 in the first and second rotating directions over an angle theta. Aradially outer portion of the outer engagement portion 116 of the driveplate 103 is inserted into the slit 140. Thereby, the end of the firstmovement restricting portion 117 of the outer engagement portion 116comes into contact with the edge of the slit 140 when the torsion anglebetween the input and output members increases to a certain value, andthereby the relative rotation between them stops.

Since the driven plate 105 and the support ring 106 are formed of theindependent members, respectively, these parts can have simpleconfigurations and structures, although the parts increase in number.Therefore, the whole work for the production can be simpler than that inthe case where these parts are formed of a single member.

Operation of the above described device is provided below.

Torque of the crank shaft of the engine is supplied to the front cover150 via a flexible plate (not shown). The torque is transmitted to theunillustrated impeller. When the impeller rotates, the working fluidflows toward the turbine 152 to rotate the same. The torque of theturbine 152 is output to the main drive shaft through the unillustratedturbine hub.

When the speed ratio of the torque converter increases and the maindrive shaft attains a predetermined rotation speed, the working fluidbetween the piston 102 and the front cover 150 is drained through theinterior of the main drive shaft. As a result, a pressure differencepresses the piston 102 to the friction surface 151 of the front cover150. Thereby, the torque of the front cover 150 is transmitted to theturbine 152 through the lockup mechanism 101. Thus, the front cover 150is mechanically coupled to the turbine 152, and the torque of the frontcover 150 is output directly to the main drive shaft without passingthrough the impeller.

In the engaged state of the lockup clutch, the input support portion ofthe drive plate 103 pushes the damper in the first rotating directionR1, and the damper pushes the engagement portion 105b of the drivenplate 105. Thereby, the torque is transmitted from the piston 102 to thedriven plate 105.

In the engaged state of the lockup clutch, the lockup mechanism 101transmits the torque and also operates to absorb or damp the torsionalvibration transmitted from the front cover 150. More specifically, thefirst and second coil springs 107 and 108 forming the damper expand andcontract between the drive plate 103 and the driven plate 105, wherebythe torsional vibration is absorbed and damped.

In this embodiment, the first and second coil springs 107 and 108 arecoupled to operate in series so that the piston 102 can rotate through alarge angle with respect to the driven plate 105. Therefore, largemaximum torsion angle characteristics can be ensured in spite of thefact that the dampers are located at the radially outer positions of thetorque converter and the lockup mechanism 101. The rigidity (springconstant) of the first coil spring 107 and that of the second coilspring 108 are different from each other and therefore provide thespring characteristics having two stages. Therefore, the input torsionalvibration having the amplitude and frequency of various values can bedamped efficiently.

Since the entire lockup mechanism 101 rotates in the torque transmittingoperation, the first and second coil springs 107 and 108 for absorbingand damping the vibration receive a centrifugal force. This centrifugalforce pushes the first and second coil springs 107 and 108 radiallyoutward. Since the first and second coil springs 107 and 108 arearranged in series, the circumferentially middle portion of the damperis likely to protrude radially outward. In this embodiment, however, thecircumferentially opposite ends of the damper are supported by the firstand second movement restricting portions 117 and 129 so that africtional resistance is suppressed between the circumferentiallyopposite ends of the damper and the cylindrical portion 125 of thesupport ring 106. Further, the third movement restricting portion 122 ofthe intermediate plate 104 restricts the radially outward movement ofthe circumferentially middle portion of each damper. As a result, africtional resistance is suppressed between the circumferentially middleportion of the damper and the cylindrical portion 125. As describedabove, the damper, which is formed of the first and second coil springs107 and 108 arranged in series in the rotating direction and thereby hasa large maximum torsion angle, has the circumferentially opposite endsand the circumferentially middle portion which are restrained fromradial movement. Therefore, the frictional resistance of the first andsecond coil springs 107 and 108 with respect to the other member(support ring 106) is remarkably reduced as compared with the prior art.

The torsion operation of the lockup mechanism 101 will be describedbelow further in detail. In the following description the driven plate105 rotates relatively to the piston 102. The driven plate 105relatively rotates in the second rotating direction R2 from the neutralor initial position in FIG. 20. In this case, the engagement portion105b and the spring engagement portion 128 push the first spring seat130 in the second rotating direction R2. In this operation, the forwardend in the first rotating direction R1 of the first coil spring 107 andthe cylindrical portion 125 move in the substantially same direction asthe driven plate 105 so that a frictional resistance is unlikely tooccur between the first coil spring 107 and the cylindrical portion 125.While the torsion angle is small, the first coil spring 107 of a lowrigidity is compressed to a large extent, and the second coil spring 108is compressed only to a small extent. Although a speed difference ispresent between the second coil spring 108 and the cylindrical portion125, the forward end in the second rotating direction R2 of the secondcoil spring 108 is supported by the first movement restricting portion117 of the drive plate 103, and therefore is restrained from radiallyoutward movement so that the frictional resistance is unlikely to occurbetween the second coil spring 108 and the cylindrical portion 125. Whenthe torsional angle further increases, the first movement restrictingportion 117 of the drive plate 103 comes into contact with the edge ofthe slit 140 of the cylindrical portion 125 so that the relativerotation between the piston 102 and the driven plate 105 stops.

Since the first movement restricting portion 117 is provided with theguide surface 118, the outer peripheral surface of the forward end inthe second rotating R2 of the compressed second coil spring 108 isguided radially inward by the guide surface 118. Since the secondmovement restricting portion 129 is provided with the guide surface129a, the outer peripheral surface of the forward end in the firstrotating R1 of the first coil spring 107 is guided radially inward bythe guide surface 129a. The guide surfaces 118 and 129a also guideradially inwardly the ends of the first and second coil springs 107 and108 to move then smoothly to the initial positions when the compressedcoil springs 107 and 108 expand toward the initial forms to bring theirends into contact with the first and second movement restrictingportions 117 and 129 again. Therefore, even in such a structure that thefirst movement restricting portions do not restrict the radially outwardmovement of the opposite ends of the first and second coil springs inthe free state (i.e., the opposite ends are spaced from the supportportions of the input or output member), the guide surfaces reliablyguide radially inwardly the ends of the first and second elastic memberswhen these members are compressed so that the a sufficient space can bekept by the first and second elastic members with respect to the membersarranged radially outside them. As a result, an unnecessary frictionalresistance is unlikely to occur when the torsional vibration istransmitted.

Since the first movement restricting portion 117 is formed of theprojection at the outer periphery of the drive plate 103, this portionhas a simple structure and therefore can be processed easily. The secondmovement restricting portion 129 also has a simple structure which canbe produced by slightly deforming the cylindrical portion 125. Asdescribed above, the simple structures allowing easy processing are usedfor supporting the circumferentially opposite ends of each damper forreducing an unnecessary frictional resistance.

The first and second movement restricting portions 117 and 129 arearranged radially outside the forward end in the first rotatingdirection R1 of the first coil spring 107 and the forward end in thesecond rotating direction R2 of the second coil spring 108, and restrictthe radially outward movement of these ends by the contact with theouter peripheries of these ends. Therefore, a superior effect can beachieved by the simple structures.

The cylindrical portion covering the outer periphery of the damper maybe provided at the input member or the intermediate member.

According to the invention, the seat member for restricting the radiallyoutward movement of the elastic member is employed so that thefrictional resistance between the ends of the elastic member and theother member arranged radially outside the elastic member is suppressed,and the minute torsional vibration can be effectively absorbed.

Also, the invention employs such a structure that the above frictionalresistance between the input member and the output member is suppressedduring the relative rotation in one of the relatively rotatingdirections, and the frictional resistance is generated during theopposite direction. Thereby, such an effect can be achieved in additionto the above effect that a relatively large vibration which occursduring engaging and disengaging operations of the clutch can beeffectively damped.

In the lockup mechanism of the torque converter according to anotheraspect of the invention, the first movement restricting portion providedat the input member and the second movement restricting portion providedat the output member always restrict the radially outward movement ofthe opposite ends of the first and second elastic members when theseelastic members are compressed in accordance with the relative rotationbetween the input and output members. As a result, a frictionalresistance of the first and second elastic members with respect to theother members is reduced.

Various details of the present invention may be changed withoutdeparting from its spirit or its scope. Furthermore, the foregoingdescription of the embodiments according to the present invention areprovided for illustration only, and not for the purpose of limiting theinvention as defined by the appended claims and their equivalents.

What is claimed is:
 1. A lockup damper mechanism of a lockup clutchmechanism in a torque converter, said lockup mechanism being providedfor mechanically transmitting a torque from an input rotary member to anoutput rotary member, said lockup damper mechanism being operable toabsorb or damp a vibration transmitted from the input rotary member tothe output rotary member, said lockup damper mechanism comprising:aninput member coupled to the input rotary member for receivingtransmitted torque; an output member outputting the torque to the outputrotary member; a coil-shaped elastic member disposed between said inputmember and said output member; and a seat member having a loose-fitportion extending into one end of said elastic member, said seat memberbeing attached to one of said input and output member, and beingoperable to restrict a radially outward movement of the end of saidelastic member.
 2. The lockup damper mechanism of the torque converteraccording to claim 1, whereinsaid input member has a holding portiondisposed radially outside said elastic member and is circumferentiallyengaged with said elastic member, said output member is fixed to saidoutput rotary member, and is circumferentially engaged with said elasticmember, and said seat member is attached to said output member.
 3. Thelockup damper mechanism of the torque converter according to claim 2,whereinsaid seat member is attached to a portion of said output memberopposed to a forward end of said elastic member with respect to arotating direction of the torque converter.
 4. The lockup dampermechanism of the torque converter according to claim 1, whereinsaidloose-fit portion of said seat member has a converging, tapered shape.5. The lockup damper mechanism of the torque converter according toclaim 1, further comprising a holding member disposed radially outsidesaid elastic member for rotation together with one of said input memberand said output member, wherein said seat member restricts the radiallyoutward movement of one end of said elastic member.
 6. The lockup dampermechanism of the torque converter according to claim 5, wherein saidholding member is formed with engagement portions and said seat memberformed with outer and inner peripheral surfaces which engage saidengagement portions with said lockup damper mechanism in a torsion freestate.
 7. The lockup damper mechanism of the torque converter accordingto claim 1, whereinsaid input member has a holding portion disposedradially outside said elastic member and is circumferentially engagedwith said elastic member, said output member is fixed to said outputrotary member, and contacts said elastic member in a circumferentialdirection, and said seat member has a first engagement portionengageable with said input member, a second engagement portionengageable with said output member, and a support portioncircumferentially supporting said elastic member, and is operable torestrict the radially outward movement of the end of said elastic memberwith at least one of said first and second engagement portions engagedwith said input or output member.
 8. The lockup damper mechanism of thetorque converter according to claim 1, whereinsaid input member has aholding portion arranged radially outside the elastic member, said seatmember has an engagement portion engageable with said output member, isattached to the forward end, in the rotating direction of the torqueconverter, of said elastic member, and is operable to restrict theradially outward movement of the end of said elastic member when saidengagement portion is engaged with said output member.
 9. The lockupdamper mechanism of the torque converter according to claim 1, furthercomprising a holding member arranged radially outside said elasticmember and being rotatable together with one of said input and outputmembers.